Centralized traffic controlling system



3m. 2, 1934. c. s. BUSHNELL CENTRALIZED TRAFFIC CONTROLLING SYSTEM Filed Aug. 11, 1931 mag Patented Jan. 2, 1934 UNITED STATES CENTRALIZED TRAFFIC CONTROLLING SYSTEM Charles S; Bushnell, R to General Railway ter, N. Y.

Application August 1 1,-

This'invention relates to relay systems, and more particularly pertains to relay systems employed in centralized trafiic control systems for railroads.

It has been found desirable to employ in relay systems what is commonly called a polar magnetic stick type relay toaccomplish various storing functions therein. Such a relay isresponsive to the application of current of opposite polarities to operate its contacts to either of .two extreme positions in accordance with the particular polarity applied, and maintains its contacts inthe last operatedposition. Such a relay is made responsive to opposite polaritiesby the use of permanent magnets and is held in its operated positions by the same permanent magnets.

In accordance with the present invention, it is proposed to provide control fora neutral relay in such a manner that its contacts are operated to one or the other of two positions in accordance with the application of current of opposite polarity. The use of a neutral relay in accordance with the present invention, thus entirely eliminates employing permanent magnets to accomplish the usual polarizing and storing function of a magnetic stick type relay. This is particularly desirable inasmuch as permanent magnets slowly lose their magnetism with age and use.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawing and in part pointed out as the description of the invention progresses.

9 Claims.

cally and certain conventional illustrations have been employed, the drawing having been made more with the purpose of making it easy to understand the principles and mode of operation than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice.

The various relays and their contacts are illustrated in a conventional manner, and symbols are used to indicate connections to the terminals of batteries or other sources of electric current In'describing theinvention in detail, reference instead of showing all the wiring connections to ochester, N. Y., assignor Signal Company, Roches- 1931. Serial No. 556,423

these terminals. The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of direct current; and the circuits with which these symbols are used, alwayshave current flowing in the same direction. The symbols (3+) and (3-) indicate connections to the opposite terminals of a suitable battery or other direct current source which has a central or intermediate tap designated (CN); and the circuits with which these symbols are used may have current flowing in one direction or the other depending upon the particular terminal used in combination with the intermediate tap (ON). I While certain features of the invention are applicable to and useable with any type of relay system, the specific embodiment of the invention illustrated has been shown in aform adapted for use with a selective communication system of the duplex coded type as employed in centralized trafiic control systems for railroads, as shown and described for example in the pending application of N. D. Preston et al., Ser. No. 455,304, filed May 24, 1930.

In systems of this type, a line circuit is employed to connect a central station with a single or a plurality of field stations, which line circuit has applied thereto a series of positive and nega tive time spaced impulses. The line circuit is usually deenergized between the application of successive impulses. The particular sequence of polaritiesis usually determined by the codes or controls transmitted so that the system of the present invention has been arranged to take care of any sequence of polarities which may be possible to be placed upon the line circuit.

With reference to the drawing, a three position polar line relay L is shown as included in a line circuit having one end connected to the midtap of a. batteryindicated by (CN) with the opposite end of the line capable of receiving positive, negative or zero (line deenergized) impulses as indicated by the legend (B+), (B-) or zero respectively. This three position polar relay has its contacts biased to neutral deenergized positions, which contacts are operable to right or left hand extreme positions by the application of positive or negative impulses respectively.

A quick acting line repeating neutral relay LR is used to repeat the energized condition of the polar line relay L irrespective of the polarityap plied to the line relay; while the slow acting line repeating neutral relay SL repeats the energized condition of the relay L and maintains its contacts in energized positions during the application circuits are obvious from the drawing.

of a series of impulses to the line relay, but drops its contacts after the line relay has been deenergized for a predetermined period of time.

A neutral multiple winding impulse storing relay IS is provided. This relay has two separate windings having the same relation to the core or magnetic structure thereof, one winding of which may at times be energized by current of reverse polarity. By neutral relay is meant a relay which by and of itself cannot distinguish direction of current flow, unless, of course, a neutralizing winding is employed in which case relative direction of current flow in these windings becomes a factor. Neutral relays, generally meaning soft iron armature relays, as is the case with respect to relay IS, are very easily and cheaply built, are especially rugged and reliable, and have a very long life, this to a large extent by reason of the fact that the armature may be operated about an external bearing rather than a centrally located bearing, thereby releasing the. arc or movement and the strain and wear on such bearing. Also, as already pointed out hereinbefore, a neutral relay does not require a permanent magnet, or equivalent means, which are somewhat uncertain in their performance, especially over a long period of time. As will presently appear, theneutral relay IS responds distinctively to two positions of the contact 6 of the polar relay L but does not change its former position as this contact 6 shifts to the third, or middle position. This relay is employed to store the particular polarity of the successive impulses applied to the line relay L. In other words, when the line relay L is energized with one polarity, the. impulse storing relay is energized with one polarity and is maintained energized by a stick circuit irrespective of the subsequent deenergization of the line relay L; while if the line relay L is energized with the opposite polarity, the impulse storing relay IS is not energized and remains deenergized irrespective of the subsequent deenergization of the line relay L. On the other hand, if the relay IS has once been energized closing its stick circuit, and the line relay L is then energized with said opposite polarity, the control winding of the relay IS is energized with the opposite polarity which neutralizes the effect of the stick winding and causes the contacts of r the relay to drop away.

It is believed that the nature of the invention, its advantages and characteristic features can be best understood with further description being set forth from the standpoint of operation.

Operation With the relay system of the present invention in its normal condition, all the relays thereof are in normal deenergized positions.

For convenience let us assume that a series of time spaced impulses are placed upon the line circuit including the three position biased to neutral polar line relay L. In accordance with the character of these impulses, the line relay L actuates its contacts 5 and 6 to either right or left hand energized positions. Upon the application of the first impulse, irrespective of its character, the contacts of the quick acting line repeating relay LR are immediately actuated to energized positions and a short time thereafter the contacts of the slow acting line repeating relay SL are also actuated to energized positions through circuits closed by the contact 5 of line relay L, which During each succeeding impulse of the series, the line repeating relay LR is energized and picks up its contacts; while between the impulses it is deenergized and drops its contacts. The line repeating relay SL is sufliciently slow acting to maintain its contacts 12 closed between the successive impulses and opens them only at the end of the series after a predetermined time.

We may now consider the control of the impulse storing relay IS. If the first impulse of a series is positive (B+), a circuit is completed for the control winding (upper winding), after the relay SL is picked up, from (3+) through polar contact 6 of relay L in a right hand position, wire '7, front contact 8 of line repeating relay LR, wire 9, upper winding of relay IS, wires 10 and 11, front contact 12 of line repeating relay SL, to (CN). The contacts of the impulse storing relay IS are thus actuated to energized positions.

During the time between this first impulse and the next, the line relay L and the line repeating relay LR are deenergized, while the contacts of theslow acting line repeating relay SL remain in energized positions. During such time period and so long as the relay SL is picked up, the impulse storing relay IS is maintained energized in ac- ..I=

cordance with its last control through a stick circuit from (13+), through front contact 13 of relay IS, wire 14, lower winding of relay IS, wires 15 and 11, front contact 12 of relay SL, to (ON).

iJU

It is noted that this stick circuit is completed as 1".3'

soon as the relay IS is energized.

On the other hand, if the first impulse is negative (13-), the contact 6 of relay L is actuated to a left hand. position, but as the relay IS is deenergized and. contact 16 is open, there is no circuit completed. Thus, the relay IS is deenergized and remains so irrespective of the deenergization of the relay L.

Upon the application of the next impulse (second) to the'line circuit, the relay L is energized 1 in accordance with the polarity and the relays LR and SL are again energized, thus picking up the contacts of relay LR and continuing to hold up'the contacts of relay SL.

If this second impulse is positive (3+), acir- 12*.

cuit is completed for energizing the control winding of relay IS, as above pointed out. Thus, if the preceding impulse was positive, the relay IS is maintained picked up as the current in the control winding (upper winding) flows in thesame direction as the current in the stick winding (lower winding). But if the preceding impulse was negative, then of course the relay IS is now picked up closing its stick circuit. In either case the relay IS is maintained up in spite of the de- 115".

energization of the relay L and so long as the contacts 12 of relay SL remain closed.

On the other hand, if this second impulse of the series is negative (B), the contacts 5 and 6 are moved to left hand positions. ceding impulse was negative, the relay IS was already down and remains so by reason of open contact 16. But, if the preceding impulse was positive, the relay IS was already energized Thus, if the pre- 31 through its stick circuit and is now by closing 3 a second energizing circuit in effect deenergized by current flowing in the control winding from (B), through front contact 16 of relay IS, wire 17, polar, contact 6 of line relay L in a left hand position, wire '2, front contact 8 of relay LR, wire 9, upper winding of relay IS, wires 10 and 11, front contact 12 of relay SL, to (ON) It is noted that the current flowing through the control winding has a direction opposite to that flowing. in the stick winding of the relay IS. As these windings are constructed to have substantially the same number of ampere turnsythe magnetic fluxes produced by the two windings, when thus energized at the same time, neutralize each other so that the resulting flux acting upon the armature of the neutral relay I5 is substantially zero, which causes or allows the armature to drop away. If desired, the control winding (upper winding of relay IS) may be provided with a sufficient number of additional ampere turns to reduce the residual magnetism of the relay core to zero. Thus, it can be seenthat a negative impulse causes the impulse storing relay IS, if energized, to be deenergized and to remain deenergized dur-' ing the time separating this second impulse and the third impulse. In other words,the neutralizing of the fluxes produced by the control and stick windings causes the relay in effect to be deenergized which opens its contacts 13 and 16 and actually deenergizes both windings.

It can be seen from the above, that the function of the contact 16 is to prevent the impulse storing relay IS from being momentarily energized and deenergized when the line relay L is energized with negative energized on the last impulse.

impulses. In other words, if (B) is applied directly to contact 6 in a left hand position, the relay IS would be momentarily energized and then dropped as soon as the front contact 13 should be closed and the I relay IS would thus be intermittently energized and deenergized so long as the contact 6 remained in a left hand position.

The application of the remaining impulses of the series is effective to control the relay IS in I accordance with their polarity in a similar manner as described for the first two impulses. At the end of the last impulse of the series of time spaced impulses, the slow acting relay SL is, de-

M v energized after a predetermined time, thus caus- (iii ing the relay IS to be deenergized if it had been The embodiment of the present invention has thus illustrated how a neutral relay may be controlled in accordance with the application of opposite polarities to its a control winding. The relay thus controlled may be employed for controlling such circuits as desired, such control being merely indicated by a legend on the drawing.

Also, it is to be understood that one or the other of contacts 8 and 12, or both, may be omitted without departing from the invention. The insertion of contact 8 illustrates how the control of a neutral storing relay may be interrupted; while the insertion of contact 12 illustrates how the control of the relay is interrupted and at the same time restoring it to a particular position. It is to be further understood that the contact 6 might be a two position contact, or might be replaced by a plurality of contacts on different relays or devices and still practice the present invention.

Having thus described a relay system as one specific embodiment of the present invention, it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations and alterations may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention except as limited by the appended claims.

Having described my invention, I now claim:

1. In combination, a neutral relay having contacts capable of assuming either'of two positions, a control circuit for said neutral relay including a first winding, and means including a second winding and a stick contact in series therewith for causing the contacts to assume one or the other of their two positions depending upon the direction of current flow in said control circuit.

2. In combination, a neutral relay having two windings, a control circuit including one of said windings, a stick circuit including the other of said windings and capable of having current flowing therein in only one direction when closed, means for causing current to flow in one direction in said control circuit for picking up the contacts of said neutral relay and closingsaid stick circuit, and means for causing current to flow in the other direction in said'control circuit only when the contacts of said neutral relay are picked up for dropping the contacts of said neutral relay, whereby said neutral relay operates its contacts to either of their two positions in accordance with the direction of current flow in said control circuit, said contacts being held in their last operated position.

3. In combination, a neutral relay having a control winding and a stick winding, a stick circuit closed when said neutral relay is energized, a control device operable to two positions, means for energizing said control winding with current flowing in one direction whereby said neutral relay is energized and said stick circuit is closed when said control device is in one of said two positions, and means for energizing said control winding with current flowing in the opposite direction when said control device is in the other of said two positions and said neutral relay is energized.

4. In combination, a three position biased to neutral polar relay, and means for storing a particular energized condition of said polar relay during a succeeding deenergization, said means comprising a neutral relay, a control winding and a stick winding for said neutral relay, a stick circuit for said stick winding, a control circuit for said control winding, and means enerizing said control circuit with current flowing in one direction or the other dependent upon 5. In combination, a line relay responsive to impulses of opposite polarity, a quick acting line repeating relay, a slow acting line repeating relay, a neutral relay for storing the condition of energization of said line relay, means retarding the response of said neutral relay to the energization of said line relay, said means including said quick acting line repeating relay and said slow acting line repeating relay, and means restoring said neutral relay to a particular position, said means including said slow acting line repeating relay.

6. In a centralized trafiic controlling system for railroads, the combination with a line circuit including a polar relay and energized intermit tently by curr nts of various polarities, a neutral relay having two windings, and two circuits for said neutral relay controlled by said polar relay and causing said neutral relay to assume a different position for each change of polarity applied to said line circuit.

7. In a centralized traffic controlling system for railroads, the combination with a line circuit including a polar relay and energized intermittently by currents of various polarities, a neutral relay having two windings, a stick circuit for said neutral relayincluding one of said windings and; energizable by current of one polarityonly, and a second circuit for said, neutral relayand controlled by said polar relay and energized by a current of polarity depending on the polar position assumed by said polar relay but energized bycurrent of one of said polarities only if said neutral relay is, then in an energized position.

8. In a centralized traflic controlling system for railroads, the combination with a line circuit including a polar relay and energized intermittently by currents of various polarities, a neutral relay having two windings, a pick-up circuit for said neutral relay closed when said polar relay assumes one polar position, a stick circuit for said neutral relay including a front contact of said neutral relay, and a bucking circuit for opposing the magnetic effect of said stick circuit effective only if said polar relay assumes the opposite polar position and when said neutral relay assumes its energized position.

9. In a centralized traflic controlling system for railroads, the combination with a line circuit including a polar relay and energized intermittently by currents of various polarities, a neutral relay having two windings, a pick-up circuit for said neutral relay closed when said polar relay assumes one polar position, a stick circuit for said neutral relay including a front contact of said neutral relay, and a bucking circuit for opposing the magnetic effect of said stick circuit to deenergize said neutral relay effective only if said polar relay assumes the opposite polar position and when said neutral relay assumes its energized position, and other means for effecting deenergizationof said neutral relay effective only if said line circuit remains deenergized for more than a predetermined time.

CHARLES S. BUSHNELL. 

